Various roofing systems for fixing flat shingles or tiles to a roof are known in the prior art.
For example, Australian Patent No. 672286 discloses a tile roofing system in which spaced apart parallel joining strips extend between a pair of adjacent battens and wherein each shingle or tile is supported along its opposite margins by a pair of adjacent said strips. In this Patent specification locking means are provided integrally with a strip for securing the lower end portion of a respective tile against lifting. These strips are known in the art as “weather strips” and prevent moisture, dust etc. from passing between tiles and into the roof space. In Patent No. 672286 two forms of the integral locking means are disclosed. In one embodiment, integral tabs are provided at the lower end of each weather strip and are bent over a lower edge of a respective tile or shingle. In a second embodiment, each weather strip has an upstanding hook generally centrally positioned therein, and this hook projects upwardly to engage the lower end of a shingle or tile in the next uppermost row from the weather strip to prevent lifting of that shingle or tile.
GB Patent Application No. 2160559 shows a weather strip having an upstanding hook like member which engages the lower end of a shingle or tile in the next uppermost shingle or tile row from the weather strip. The arrangement in GB 2160559 is virtually identical to the arrangement disclosed in the Australian Patent No. 672286.
DE 800784 discloses a weather strip which extends between upper and lower battens, and a lower end of the weather strip is provided with tabs which engage with a lower end portion of the respective tile.
In the arrangements shown in the above documents, the various tab and hook type arrangements are provided to restrain the lower end of a respective tile to prevent its upward lift, for instance, from strong wind conditions etc.
In practice, however, installations which have used the system disclosed in, for instance, Australian Patent No. 672286 have exhibited poor weatherproofing and problems with corrosion with the portion bent or extending over the lower end of the tile.
It would be advantageous if an alternative retention system for securing tiles, especially flat type tiles or shingles, could be provided which would not have the corrosion problem.